Synthesis of Linear Array Antenna using Hybrid IWO/WDO Algorithm

Abstract

This paper introduces the application of a recently developed soft algorithm, hybrid WDO/IWO for synthesis of linear array antenna by optimizing the antenna parameters namely excitation amplitude, position and complex weight (excitation amplitude andphase). Single and multiple nulls are placed at desired location to minimize the interference effect. The Hybrid WDO/IWO algorithm provides optimal solution of complex antenna design problem which mostly satisfies the requirement of todays communication world such as high gain, minimum side lobe level (SLL), minimum beam width and nulls at desired direction. Four examples are considered to demonstrate the efficiency of hybrid algorithm and results are compared with other soft computing based optimisation results reported in literature. In first example, we considered the linear array synthesis ( $N= 32$ ) with minimum SLL in the spatial region [180°, 932°] and [93°, 0°], a prescribed null at 99° and the desired beam width is set to 8.30°. The radiation pattern obtained by hybrid algorithm is compared with the conventional method, IWO and PSO algorithm and position of array element are optimized. The algorithm presented here achieves minimum side lobe level of −19.70dB as compared to −15.7dB, −17.11dB, −18.80dB and −16.93dB in IWO, WDO, PSO and BBO based designs respectively. In second example, a prescribed null is placed at 14°, two spatial region of interest for maximum SLL suppression are [8.839°, 90°] and [−8.839°, −90°] and desired beam width, null depth level (NDL) and dynamic range ratio (DRR) is set to 8.9°, −60 dB and 5 respectively in order to minimize the interference effect in initial Chebyshev array by optimizing the excitation amplitude of array element. In third example, double nulls are imposed at 14° and 26° with the spatial region of suppressed SLL [8.9118°,90°] and [8.9118°,90°], desired NDL −60 dB, desired beam width 8 : 9° and restricted DRR 6.5. In the last examples a prescribed single null is placed at −14°, desired beam width 8.7677°, desired NDL −60 dB, restricted DRR 5 and the region of interest for maximum SLL suppression are [8.66°, 90°] and [−8.4077°, −90°] and complex weight are optimized. The simlution results are compared with other reported algorithm.